The invention lies in the communications and signal processing fields. More specifically, the invention refers to a method and circuit configuration for making data signal connections between data terminals, particularly computers and PCs, which are connected to a circuit-switched switching center, and/or between these data terminals and a separate data network, in particular the Internet data network, which is connected to the circuit-switched switching center via one or more connecting nodes. The term xe2x80x9ccircuit-switched switching centerxe2x80x9d as used herein means a switching center which is appropriately designed to carry out circuit switching processes.
In the types of data signal connections considered above a transmission capacity of 56 kbit/s maximum has heretofore been usually available in analog circuit-switched networks. A transmission rate of 64 kbit/s maximum per connection has usually been available in digital circuit-switched networks. The protocol which is used for data signal transmission is mostly the so-called point-to-point protocol (PPP-RFC 1661).
To increase the transmission capacity, it is also possible in a digital circuit-switched network, in the case of an ISDN basic rate access with two B channels, to achieve a maximum transmission rate of 128 kbit/s, if both B channels are used for data signal transmission (see Protocol RFC 1717). There, two physical connections are available for the relevant data signal transmission.
The data network accesses which have been used heretofore are all based on the classical switched connection service, which was designed above all for transmission of telephone signals. This service is wherein a defined transmission bandwidth is guaranteed to a subscriber for the duration of the connection, and in that an existing connection is not in general ended from the network which is used. For this classical service, the technical implementation and dimensioning of the switching centers have been organized from the point of view of the highest availability and reliability. Very low network load is then the result of this over-dimensioning. The result would be the same if broadband switched data signal connections with the same availability and reliability were provided.
The object of the invention is to provide a method and a circuit for setting up data signal connections, which overcome the above-noted deficiencies and disadvantages of the prior art devices and methods of this kind, and which lead a way to providing the respective optimum transmission capacity for each of the data signal connections to be provided, without the network infrastructure having to be dimensioned differently from the given conditions for normal connections.
With the above and other objects in view there is provided, in accordance with the invention, a method of establishing data signal connections between data terminals (e.g. PCs) connected to a circuit-switched switching center, and/or between the data terminals and a separate data network (e.g. Internet) connected to the circuit-switched switching center via one or more connecting nodes, which comprises:
defining a normal transmission capacity in a circuit-switched switching center available for normal data signal connections;
defining a first traffic load threshold and a second traffic load threshold in the switching center (the second traffic threshold may be equal to the first traffic threshold);
if a traffic load in the circuit-switched switching center or a network including the switching center lies below the first traffic load threshold, providing additional transmission capacity for the data signal connections to be established in the switching center, in addition to the normal transmission capacity available in the switching center for the normal connections;
if the traffic load exceeds the first traffic load threshold, providing only a transmission capacity currently available for normal data signal connections for the data signal connections to be established;
after the traffic load undershoots the second traffic load threshold, providing additional transmission capacity in addition to the normal transmission capacity available for the normal connections for the data signal connections to be established.
In other words, the above objects are satisfied in that, if a traffic load below a first traffic load threshold V1 is present in the circuit-switched switching center and/or in the network which includes it, additional transmission capacity is provided for the data signal connections to be made in this switching center, in addition to the transmission capacity which is available in this switching center for normal connections (for telephone, fax, narrowband or X.25 connections). If, thereby, the above-mentioned first traffic load threshold V1 is exceeded by the relevant traffic load, only the transmission capacity which is currently available for normal connections is provided for the data signal connections which are then to be made, and in that only after the above-mentioned traffic load undershoots a second traffic load threshold V2, which at most corresponds to the first traffic load threshold V1, additional transmission capacity to that which is available for normal connections is again provided for the data signal connections which are then to be made.
The invention has the advantage that the transmission capacity which is available in the circuit-switched switching center can be made usable for data signal connections in a relatively simple way, and the usefulness which is thus created is directed at the traffic load of the relevant switching center. This means that in every case normal connections, i.e. usually telephone and fax connections or narrowband or X.25 connections, obtain the transmission capacity which they require for their signal transmission, and that only after that is additional transmission capacity provided for the data signal connections, if such capacity is still available. In this way the transmission capacity of the circuit-switched switching center is optimal, i.e. it can be exploited better than previously. It should be noted here that data applications in general are insensitive to variations or changes in the transmission capacity. It should also be noted that the method according to the invention can be used advantageously even if the first traffic load threshold V1 is set to infinity.
In accordance with an added feature of the invention, if the traffic load in the network including the circuit-switched switching center exceeds a third traffic load threshold (above, between, or below the first and second thresholds), the additional transmission capacity previously provided for data signal connections is removed from at least some existing connections.
This action, which occurs additionally to the action which was taken when the first traffic load threshold V1 was exceeded, has the advantage that, as the traffic load in the circuit-switched switching center increases, the normal connections to be set up there can be given priority in every case over the data signal connections with increased data transmission capacity. In the case that the third traffic load threshold V3 is between or below the first and second traffic load thresholds V1, V2, the resulting advantage is that additional transmission capacity can be provided for new data signal connections relatively quickly, after it has been removed from existing data signal connections. If the third traffic load threshold V3 is below the second traffic load threshold V2, the resulting advantage is a purely precautionary removal of additional transmission capacity which was previously provided.
In accordance with an additional feature of the invention, the additional transmission capacity for data signal connections is removed selectively in dependence on a relevant connection duration and/or of subscriber data of the data terminals participating in the connection. This means that the additional transmission capacity is removed taking into account the relevant connection duration and/or the subscriber data of the data terminals participating in the data signal connection. In this way the additional transmission capacity can be removed advantageously according to criteria which can be predefined, e.g. after a specified time interval, and if appropriate even without taking account of the traffic load.
Appropriately to the purpose, to distinguish data signal connections from normal connections within the circuit-switched switching center, a separate connection class signal, which can be analyzed, is output in the course of making the relevant data signal connections. In this way it is particularly easy to distinguish data signal connections from normal connections, and to control the action which was considered above, of removing additional transmission capacity which was provided for such connections.
With the above and other objects in view there is also provided, in accordance with the invention, a circuit configuration for implementing the above-outlined method. The circuit comprises:
an analysis and control device connected to a circuit-switched switching center, the analysis and control device receiving from the circuit-switched switching center information about a provision of additional transmission capacity for new data signal connections in the switching center and/or between the switching center and a separate data network, and receiving load information about a traffic load of the relevant switching center and/or of the network including the switching center;
a control device connected to an output of the analysis and control device, the control device controlling connections of the relevant switching center and outputting a control signal to the relevant switching center only when a transmission capacity exceeds a first traffic load threshold, the control signal causing the data signal connections to be made with only the transmission capacity available for normal connections, and the control device outputting a further control signal when the traffic load undershoots a second traffic load threshold for making available additional transmission capacity to the traffic capacity available for normal connections for the data signal connections then to be made.
To implement the method according to the invention, the circuit configuration which is used is preferably wherein an analysis and control device is connected to the circuit-switched switching center and, at its input, obtains from the circuit-switched switching center information about the provision of additional transmission capacity for new data signal connections in the relevant switching center and/or between the latter and the separate data network, and load information about the traffic load of the relevant switching center and/or of the network which includes it, and, at its output, is connected to a control device, used to control the connections of the relevant switching center, and outputs a control signal, upon which only the transmission capacity which is available for normal connections at the time is provided for data signal connections which are then to be made, to this control device only when a defined first traffic load threshold V1 is exceeded by the above-mentioned traffic load, and outputs a control signal only when the above-mentioned traffic load undershoots a second traffic load threshold V2, which at most corresponds to the first traffic load threshold V1 upon which control signal outputting 5 operation additional transmission capacity to that which is available for normal connections is again to be provided for the data signal connections which are then to be made. This circuit configuration is characterized by an overall relatively small circuit construction required in the above-mentioned analysis and control device to output control signals to the control device which controls the switching center on the basis of the current traffic load, whereupon the control device enables or prevents the provision of additional transmission capacity for the data signal connections to be made. It should also be noted here that the above-mentioned network, the traffic load of which is taken into account, includes not only the above-mentioned switching center and possibly the data network, but also other parts of the network which are involved in data signal connections, such as the connecting nodes which are connected to the data network, and individual connecting routes.
Appropriately to the purpose, when a traffic load which exceeds a third traffic load threshold V3, which is either above or between or below the first and second traffic load thresholds V1, V2, occurs in the circuit-switched switching center, the analysis and control device outputs a control signal, which causes the removal of additional transmission capacity which was provided for previously existing data signal connections from at least some of these data signal connections, to the control device which is used to control the connections of the switching center. This has the advantage of a particularly low circuit cost to provide the transmission capacity, which would otherwise be missing, for the normal connections even in the case of increasing traffic load in the circuit-switched switching center.
Advantageously, the analysis and control device contains a memory device (table) which holds data about the data signal connections for which additional transmission capacity has been provided in the circuit-switched switching center and whose data can be used in the removal of additional transmission capacity in the relevant switching center for the data signal connections in question. This has the advantage that the required removal of additional transmission capacity can be effected at particularly low total circuit cost, without extensive intervention in the control device of the circuit-switched switching center being necessary.
The analysis and control device preferably contains a selection device which can output control signals which are used for the removal of additional transmission capacity in the circuit-switched switching device according to defined criteria (connection duration, subscriber data). This has the advantage of a relatively low circuit cost to remove additional transmission capacity according to preset criteria.
Alternatively to the implementation option which is considered above, the analysis and control device is suitably integrated in the control device which controls the circuit-switched switching center. This has the advantage of a particularly low total circuit cost for implementation of the circuit configuration according to the invention.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and circuit configuration for making data signal connections, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.